Structure of the Betts Cove Ophiolite Complex beneath the western margin of Notre Dame Bay, Newfoundland

Abstract

Ophiolitic rocks emplaced following closure of the Ordovician Iapetus Ocean outcrop around the western margins of Notre Dame Bay in western Newfoundland. Previous geological and geophysical models have interpreted the Betts Cove Ophiolite Complex (BCO) as a series of imbricate thrust slices. A new three-dimensional (3-D) model indicates that locally the BCO has the form of a northeast-trending doubly plunging syncline that was later segmented by a series of normal and high-angle reverse faults. This segmentation is interpreted in terms of a Carboniferous graben structure that is responsible for the current morphology of the Notre Dame Bay. The 3-D model incorporates new high-resolution aeromagnetic, marine magnetic, and topographic imagery. In addition, newly available structural information is used to both constrain the geometry of the geological contacts in the near surface and to map contacts in the subsurface. Calibration of the computed geophysical models was achieved using newly acquired magnetic susceptibility data. The resulting 3-D model, which is compatible with all aspects of the geological and geophysical data, provides an explanation for the distribution of Ordovician ophiolites around Notre Dame Bay.

Geophysical expression of the Leka Ophiolite, Norway, modeled from integrated gravity, magnetic and petrophysical data

“…In the Philippines, the Zambales Ophiolite Complex is divided into the Acoje and the Coto blocks, and Salapare et al (2015) were the first to define the subsurface characteristics of the two ophiolites and validate the existence of a fault boundary between the two blocks. Spicer et al (2010) using highresolution aeromagnetic maps developed a 3D model of the Betts Cove ophiolite complex in Newfoundland as a syncline with normal and high-angle reverse faults. Paleomagnetism was used to detect the age of a low-temperature alteration event during the midCarboniferous, that was previously unknown in the Shetland Ophiolite (Taylor, 1988), and Pozzi et al (1984) used paleomagnetism to define the paleo-orientation and paleo-latitude of the spreading center that had created the Xigaze ophiolite in Tibet.…”